As with all aircrafts, the aim of gyrocopters is also to have as light a construction as possible. This is especially important with gyrocopters because, in order to be approved as sport aircraft, the mass must not exceed 450 kg. Thus the goal is to construct a particularly light weight torque transmission device. However, to this effect, there are already limits on current gyrocopters which state that the torque transmission device must be designed in such a way that it withstands torque peaks. Such torque peaks can, for example, occur at the start of a pre-rotation if the pilot accelerates too early.
In U.S. Pat. No. 5,544,844 a gyrocopter is described which has a hydraulically operated coupling. With this hydraulically operated coupling, oil pressure is built up by means of a lever. This is then directed to the coupling and causes the switching procedure. With this gyrocopter there is also the problem that the pilot can engage the coupling too quickly so that the torque transmission device behind the coupling is overworked. In order to avoid this, the torque transmission device must be oversized, as described above.
In U.S. Pat. No. 6,062,508 an aircraft is described which has a main rotor for taking off and landing, as well as wings for cruising flight. For the switching of the motor from the main rotor to a propeller a multi-plate coupling is provided. For a combination aircraft of this type, enough power must be transmitted to the main rotor so that a sufficiently large lift can be generated for the aircraft to take off. This requires a high-powered motor and a powerful torque transmission device. The requirements for an aircraft according to this document are therefore not comparable with the requirements for a gyrocopter. In particular, the fact that a torque transmission device must be oversized is not a problem with combination aircrafts, as such large amounts of power must be transmitted when taking off that peak power outputs created when engaging the coupling can be intercepted without any further measures.
In U.S. Pat. No. 7,448,571 B1 a gyrocopter is described which has a bracket, under which the rotor blades of the main rotor are oriented, that is automatically adjusted. The exact arrangement of the coupling is not described further in the printed description.
In U.S. Pat. No. 2,712,911 a combination aircraft is described which can be driven as a fixed wing aircraft as well as a rotary wing aircraft, and has a magnetic coupling. It has emerged that magnetic couplings of this sort are unsuitable for use in gyrocopters, as the generator needed for the creation of the necessary currents creates a large additional weight.
In DE 10 2007 004 168 A1 and DE 10 2007 032 488 A1 pneumatic couplings for land vehicles are described.